Java实现监控多个线程状态的实现

场景：需要启动多线程处理事情，而在所有事情做完之后，需要修改系统状态；那么如何判断所有线程（事情）都做完了呢？这就需要判断所有当前运行的线程状态了。

 

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;

/**
 * 测试监控类
 *
 * @author
 *
 */
public class WatchThread {

 /**
  * 测试函数
  *
  * @throws InterruptedException
  */
 public void testThread() throws InterruptedException {
  int threadNum = 10;
  // 初始化countDown
  CountDownLatch threadSignal = new CountDownLatch(threadNum);
  // 创建固定长度的线程池
  Executor executor = Executors.newFixedThreadPool(threadNum);
  for (int i = 0; i < threadNum; i++) { // 开threadNum个线程
   Runnable task = new TestThread(threadSignal);
   // 执行
   executor.execute(task);
  }
  threadSignal.await(); // 等待所有子线程执行完
  // do work
  System.out.println(Thread.currentThread().getName() + "+++++++结束.");
 }

 /**
  * 测试函数
  */
 public static void main(String[] args) throws InterruptedException {
  WatchThread test = new WatchThread();
  test.testThread();
 }

 /**
  *
  * @author jill
  *
  */
 private class TestThread implements Runnable {
  private CountDownLatch threadsSignal;

  public TestThread(CountDownLatch threadsSignal) {
   this.threadsSignal = threadsSignal;
  }

  public void run() {
   System.out.println(Thread.currentThread().getName() + "开始...");
   // do shomething
   System.out.println("开始了线程：：：：" + threadsSignal.getCount());
   // 线程结束时计数器减1
   threadsSignal.countDown();
   System.out.println(Thread.currentThread().getName() + "结束. 还有"
     + threadsSignal.getCount() + " 个线程");
  }
 }

}